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| United States Patent |
6,254,992
|
|
Kato
|
July 3, 2001
|
Support for recording sheet
Abstract
A support for recording sheet in which there is no film cracking, the
occurrence of die-lip stripes is inhibited, and which has excellent image
sharpness and has excellent light fading resistance. The support for
recording sheet is provided with a substrate having an image printing side
and another side opposite the image printing side, a water resistant resin
coating layer provided on each side of the substrate, at least the resin
coating layer provided on the image printing side containing a titanium
dioxide pigment, the titanium dioxide pigment including a titanium dioxide
having a particulate surface treated by a silane coupling agent and
aluminum phosphate in an aqueous slurry state, with a treatment amount of
the aluminum phosphate with respect to the titanium dioxide being from
0.05 wt % to 1.2 wt %.
| Inventors:
|
Kato; Shinji (Shizuoka-ken, JP)
|
| Assignee:
|
Fuji Photo Film Co., Ltd. (Kanagawa, JP)
|
| Appl. No.:
|
659608 |
| Filed:
|
September 11, 2000 |
Foreign Application Priority Data
| Sep 14, 1999[JP] | 11-259960 |
| Current U.S. Class: |
428/405; 106/443; 428/407; 428/447; 428/511; 428/513; 430/510; 430/523; 430/536; 430/538 |
| Intern'l Class: |
G03C 001/79; C09C 001/36; B32B 015/02; B32B 017/02; B32B 023/08 |
| Field of Search: |
430/538,523,510,536
428/405,407,447,511,513
103/443
|
References Cited
U.S. Patent Documents
| 3501298 | Mar., 1970 | Crawford | 96/85.
|
| 5820977 | Oct., 1998 | Shirakura et al. | 428/328.
|
| Foreign Patent Documents |
| 0 327 768 A2 | Aug., 1989 | EP | .
|
| 0 757 284 A1 | Feb., 1997 | EP | .
|
| 1 400 378 | Sep., 1965 | FR.
| |
| 2 042 573 | Sep., 1980 | GB | .
|
| 10-307367 | Nov., 1998 | JP | .
|
Primary Examiner: Schilling; Richard L.
Attorney, Agent or Firm: Sughrue, Mion, Zinn, Macpeak & Seas, PLLC
Claims
What is claimed is:
1. A support for recording sheet comprising:
(a) a substrate having an image printing side and another side opposite the
image printing side;
(b) a water resistant resin coating layer provided on each side of the
substrate, at least the resin coating layer provided on the image printing
side containing a titanium dioxide pigment, the titanium dioxide pigment
including a titanium dioxide having a particulate surface treated by a
silane coupling agent and aluminum phosphate in an aqueous slurry state,
with a treatment amount of said aluminum phosphate with respect to said
titanium dioxide being from 0.05 wt % to 1.2 wt %.
2. A support for recording sheet according to claim 1, wherein the
treatment amount of said aluminum phosphate with respect to said titanium
dioxide is 0.1 wt % to 0.8 wt %.
3. A support for recording sheet according to claim 1, wherein said silane
coupling agent is at least one selected from compounds represented by the
following formula (1):
(R.sup.1).sub.n --Si (OR.sup.2).sub.4-n (1)
wherein, R.sup.1 is a hydrocarbon group containing at least one of an alkyl
group, a vinyl group, and a methacryl group, and which has no more than 10
carbons, R.sup.2 is a methyl group or an ethyl group, n is an integer of 1
to 3, and if n.gtoreq.2, so that there is a plurality of R.sup.1, each
R.sup.1 can be the same or different.
4. A support for recording sheet according to claim 1, wherein a treatment
amount of said silane coupling agent with respect to said titanium dioxide
is 0.05 wt % to 3.0 wt %.
5. A support for recording sheet according to claim 1, wherein the
treatment amount of said silane coupling agent with respect to said
titanium dioxide is 0.5 wt % to 2.0 wt %.
6. A support for recording sheet according to claim 1, wherein a mean
particle diameter of the titanium dioxide is 0.1 to 0.4 .mu.m.
7. A support for recording sheet according to claim 1, wherein at least
said water-resistant resin coating layer provided on the image printing
side further contains a blueing agent.
8. A support for recording sheet according to claim 1, wherein at least one
of water-resistant resin coating layers provided on the image printing
side is a layer containing the titanium dioxide pigment in an amount of 13
wt % or more.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a support for recording sheet. More
specifically, the present invention relates to a support for recording
sheet which is provided with a substrate having disposed on both sides
thereof a coating layer of a water-resistant resin, which support for
recording sheet has excellent image sharpness (resolution) and excellent
image light-fading resistance.
2. Description of the Related Art
Conventionally, support for recording sheets coated with a resin on both
sides, such as photographic printing paper, thermographic paper, full
color thermographic paper, and the like have been known. In particular,
titanium dioxide, pigments, blueing agents (including blue pigments),
fluorescent brighteners, and the like have been included in the coating
layer of the paper used for photographic printing paper (U.S. Pat. No.
3,501,298).
The titanium dioxide used in this case has an effect of heightening the
efficiency of light reflectance, and it is known that the more the content
of the titanium dioxide is increased, the more image resolution is
improved.
At the time a coating layer of a water-resistant resin is formed, the
water-resistant resin which contains titanium dioxide is melted and
extruded in the form of film from a slit die for a short period of time.
However, when the titanium dioxide is incorporated in the resin coating in
an amount of 20 wt % or more and the molten extrusion is conducted at a
discharge temperature of 290.degree. C. to 350.degree. C., as has
conventionally been the case, cracks (hereinafter referred to as "film
cracking") are caused in the coating layer of the water-resistant resin,
and stripes (hereinafter referred to as "die-lip stripes") are easily
generated at the die-lip portion of the extruder.
When such film cracking occurs, the external appearance of the product not
only deteriorates, but also, the product is deprived of its commercial
value due to the loss of its water-resistant capability. Further, when
die-lip stripes are generated, consecutive stripes are formed in the
longitudinal direction on the surface of the manufactured film or
laminate. Therefore, not only does the external appearance of the product
deteriorate remarkably, but even during secondary processing such as
drawing, the transparency of the film is non-uniform, and thus the
commercial value of the product is lowered considerably.
In order to overcome such drawbacks, as the applicants of Japanese Patent
Application Laid-Open (JP-A) No. 10-307367 have already noted and
disclosed, by using a titanium dioxide pigment in which the particle
surface of the titanium dioxide to be used has been subjected to a
wet-process silane coupling agent coating treatment, the titanium dioxide
pigment can easily be incorporated in an amount of 20 wt % or more in a
polyolefine resin layer. Therefore, even when the water-resistant resin is
extrusion molded at a melting temperature of around 325.degree. C., there
are no occurrences of film cracking, die-lip stripes and the like.
The present inventors examined in detail the aforementioned high-resolution
support for recording sheet. It was found that with the silane coupling
agent coating treatment, although the titanium dioxide can be melted and
extruded at a high temperature, the generation of die-lip stripes cannot
be controlled completely since the activity of the titanium dioxide is not
inhibited. It was also noted that there is a tendency for the light fading
resistance of the print surface of the support for recording sheet to
deteriorate.
Further, JP-A No. 10-307367 discloses that by surface treating the titanium
dioxide with Al.sub.2 O.sub.3, aggregation of the titanium dioxide pigment
at the time of lamination is prevented. However, when the Al.sub.2 O.sub.3
treatment is used, effects with regard to high filling capability and
fading resistance remain insufficient.
SUMMARY OF THE INVENTION
As a result of their extensive studies to produce a high-resolution support
for recording sheet in which light fading resistance is not harmed and the
occurrence of die-lip stripes is inhibited, the present inventors devised
the present invention. Although the mechanism resulting in the working of
the present invention is not altogether clear, it was found that by using
a titanium dioxide pigment whose particle surface has been subjected to a
wet-process coating treatment with a silane coupling agent and aluminum
phosphate in an amount of 0.05 to 1.2 wt %, the titanium dioxide pigment
can easily be incorporated in an amount of 20% by weight or more in a
polyolefine resin layer without hindering the production of the titanium
dioxide pigment. Therefore, even when the titanium dioxide is extrusion
molded at a melting temperature of around 325.degree. C., there is no film
cracking, the generation of die-lip stripes is inhibited, and excellent
light-fading resistance is preserved.
In accordance with an aspect of the present invention, a support for
recording sheet comprising: (a) a substrate having an image printing side
and another side opposite the image printing side; (b) a water resistant
resin coating layer provided on each side of the substrate, at least the
resin coating layer provided on the image printing side containing a
titanium dioxide pigment, the titanium dioxide pigment including a
titanium dioxide having a particulate surface treated by a silane coupling
agent and aluminum phosphate in an aqueous slurry state, with a treatment
amount of the aluminum phosphate with respect to the titanium dioxide
being from 0.05 wt % to 1.2 wt %.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A detailed description of a support for recording sheet and a manufacturing
method thereof will be given hereinafter. In the present invention, a
layer for coating the surface of a substrate can be a single layer
structure, or a multilayer structure formed by two or three layers.
A water-resistant resin for forming a coating layer in the present
invention can be appropriately selected from resins which can be molten
and extruded at a temperature of 170.degree. C. to 345 .degree. C.
However, ordinarily, a polyolefine resin such as polyethylene or
polypropylene is used.
The polyethylene may be high density polyethylene (HDPE), low density
polyethylene (LDPE), linear low density polyethylene (L-LDPE), or the
like. However, when the rigidity of a support for a photographic printing
paper is considered to be important, polypropylene, high density
polyethylene (HDPE), linear low density polyethylene (L-LDPE), or the like
is preferably used.
These resins can be used solely, or two or more thereof can be used in
combination. In the present invention, from the standpoint of improving
image quality, titanium dioxide is contained in at least one layer of a
water-resistant resin coating layer at the side at which an image is
formed, and a blueing agent, a fluorescent brightener, or the like is
preferably contained therein. The amount of titanium dioxide which is
contained in at least one layer of a water-resistant resin coating layer
can also be 13 wt % or more, or 20 wt % or more. From the standpoint of
improving adhesiveness between the water-resistant resin coating layer and
substrate, a tackifier resin, an adhesive resin, or the like can be
included in the lowermost layer of the water-resistant resin coating layer
which comes into contact with the substrate. Further, in accordance with
the intended use of the support for recording sheet, an antioxidant, a
release agent, a hollow polymer, or the like can be appropriately
contained.
The form of the titanium dioxide pigment used in the present invention can
be either anatase-type or rutile-type. However, when the degree of
whiteness is considered to be important, an anatase-type titanium dioxide
pigment is preferably used. When sharpness is considered to be important,
a rutile-type titanium dioxide pigment is preferably used. Further, in
consideration of both the degree of whiteness and sharpness, an
anatase-type titanium dioxide pigment and the rutile-type titanium dioxide
pigment can be used in combination. Alternately, a layer containing
titanium dioxide may be divided into two layers, and an anatase-type
titanium dioxide may be added to one layer while a rutile-type titanium
dioxide is added to the other layer.
A mean particle diameter of the titanium dioxide pigment is preferably 0.1
to 0.4 .mu.m. When the mean particle diameter is less than 0.1 .mu.m, it
becomes difficult to uniformly mix and disperse the titanium dioxide
pigment in the resin coating layer. Conversely, when the mean particle
diameter of the titanium dioxide pigment exceeds 0.4 .mu.m, a sufficient
degree of whiteness cannot be obtained and protrusions are generated on
the coating surface, thus exerting an adverse effect on image quality.
The titanium dioxide pigment used in the present invention is a titanium
dioxide pigment in which the particle surface of titanium dioxide has been
subjected to a coating process with a silane coupling agent. Most
preferably, the particle surface of titanium dioxide is subjected to a
wet-process treatment with a silane coupling agent and an aluminum
phosphate while in a state of aqueous slurry during the process of
producing the titanium dioxide.
In the process of producing the titanium dioxide, the mean particle size of
the titanium dioxide is 0.10 to 0.40 .mu.m, and an aqueous slurry of 100
to 500/1 is prepared. After the slurry is maintained at a temperature of
20.degree. C. to 60.degree. C., aluminum phosphate is added and titanium
dioxide is treated by aluminum phosphate. Further, the slurry is adjusted
to a pH of 2 to 6, the silane coupling agent is added, and the resultant
mixture is hydrolyzed.
After the slurry is heated to a temperature of about 60.degree. C. to
90.degree. C., the slurry is further stirred, filtered, and washed. The
obtained cake of titanium dioxide is then dried for about 2 to 36 hours at
a temperature of 100.degree. C. to 140.degree. C., and ground by a
grinding means so that the titanium dioxide pigment can be obtained.
Methods for applying the silane coupling agent onto the surface of the
titanium dioxide generally include the following. There is a dry-process
method in which the silane coupling agent is mixed with the titanium
dioxide using a high-speed mixer such as a Henschel mixer, a jet mill, or
the like. There is a method in which the silane coupling agent and
titanium dioxide are kneaded into a thermoplastic resin (a water-resistant
resin) such as polyethylene in advance. There is also a method in which
the silane coupling agent is added to a composition of titanium dioxide
and a thermoplastic resin (a water-resistant resin) at the same time that
this composition is being mixed by a kneader to be described later.
Further, the silane coupling agent is sometimes mixed with a solvent such
as alcohol and used. However, in methods other than a wet-process
treatment, it is difficult to completely remove excessive amounts of the
silane coupling agent or the like which did not react with the surface of
titanium dioxide. For this reason, when the water-resistant resin
containing titanium dioxide which was treated by the silane coupling agent
is used for extrusion lamination, there are drawbacks in that residue of
the silane coupling agent leads to quality deficiency referred to as
"gel", and film cracking occurs when the residue is volatilized.
It is preferable that the silane coupling agent is a silane coupling agent
whose terminal end has an ethoxy group or a methoxy group. In particular,
it is desirable that the silane coupling agent is at least one type of
silane coupling agent selected from the compounds represented by the
following formula (1).
Formula (1)
(R.sup.1).sub.n --Si (OR.sup.2).sub.4-n (1)
wherein, R.sup.1 is a hydrocarbon group containing at least one of an alkyl
group, a vinyl group, and a methacryl group and which has no more than 10
carbons, R.sup.2 is a methyl group or an ethyl group, n is an integer of 1
to 3, and if n.gtoreq.2, so that there is a plurality of R.sup.1, each
R.sup.1 can be the same or different.
When R.sup.1 in formula (1) has more than 10 carbons, treatment with the
silane coupling agent in the wet-process becomes difficult since the
hydrolysis speed of the silane coupling agent itself is slow. Further,
when R.sup.1 in formula (1) has more than 10 carbons, there is the
drawback that the particles themselves of the titanium dioxide which is
treated by the silane coupling agent turn yellow. The smaller n in formula
(1) is, the faster the hydrolysis speed of the silane coupling agent in
the wet-process becomes.
A treatment amount of the silane coupling agent with respect to titanium
dioxide is preferably 0.05 to 3.0 wt %, and more preferably 0.5 to 2.0 wt
%. When the treatment amount becomes less than 0.05 wt %, surface
treatment effects by the silane coupling agent cannot be obtained.
Further, when the treatment amount exceeds 0.3 wt %, the treatment becomes
excessive with respect to titanium dioxide, and it therefore becomes
difficult to incorporate the titanium dioxide pigment in an amount of 20
wt % or more in the molten polyolefine. Moreover, there is the possibility
that the silane coupling agents will react with each other and appear in
the molten polyolefine as fine gel, leading to a noticeable deterioration
of suitability of a surface of the support.
In order to inhibit the activity of the titanium dioxide pigment, the
titanium dioxide surface may be surface treated with aluminum phosphate
when the silane coupling agent surface treatment is carried out. The
treatment amount of aluminum phosphate with respect to titanium dioxide is
0.05 to 1.2 wt %, and preferably 0.1 to 0.8 wt %.
When the treatment amount of aluminum phosphate with respect to titanium
dioxide exceeds 1.2 wt %, film cracking and die-lip stripes occur more
easily during extrusion and lamination of a water-resistance
resin-compound containing a titanium dioxide pigment in an amount of 20 wt
% or more.
On the other hand, when the treatment amount of aluminum phosphate with
respect to titanium dioxide is less than 0.05 wt %, film cracking does not
occur during extrusion and lamination even if the percentage content of
the titanium dioxide pigment within the resin compound is raised to 20 wt
% or more. However, there is the problem that die-lip stripes, which are
thought to result from the activity of the titanium dioxide not being
inhibited, become easily generated. At the same time, a fading phenomenon
in the laminated layer due to light is also easily generated.
The titanium dioxide pigment uses a higher fatty acid metallic salt, a
higher fatty acid ethyl, a higher fatty acid amide, a higher fatty acid, a
polyolefine wax, or the like, as a dispersion aid, and is kneaded into the
water-resistant resin by a kneading machine such as a two-roll, a
three-roll, a kneader, a Banburry mixer, or a continuous kneader (such as
a stone grist mill-type, a planet-type, a roll-type, or an internal
mixer-type). The obtained water-resistant resin containing titanium
dioxide is formed in a pellet shape, and used as a master batch which
contains the titanium dioxide pigment. In particular, metallic stearate is
preferably used as the dispersion aid, and more preferably, zinc stearate
is used.
The density of the titanium dioxide pigment in the pellet is preferably
about 30 to 75 wt %. Generally, the density of the dispersion aid is
preferably about 0.5 to 10 wt %. When the density of the titanium dioxide
pigment is less than 30 wt %, it becomes necessary to increase the amounts
of pellets used when the water-resistant resin layer is formed.
Conversely, when the density is more than 75 wt %, the dispersibility of
the titanium dioxide pigment deteriorates, and the pellets easily crack.
Further, the master batch which contains the titanium dioxide pigment is
preferably dried or vacuum-dried for two hours or more at a temperature of
50.degree. C. to 90.degree. C. before use.
A blueing agent can be included in the water-resistant resin coating layer.
Examples of the blueing agent include ultramarine blue, cobalt blue,
cobalt oxide phosphate, a quinacridone-based pigment, and the like, and
mixtures thereof. The particle diameter of the blueing agent is not
particularly limited, but, ordinarily, is preferably 0.3 to 10 .mu.m.
The blueing agent in the multilayer water-resistant resin coating layer of
the present invention is preferably incorporated in an amount of 0.2 to
0.4 wt % when used in the uppermost layer, and incorporated in an amount
of 0 to 0.15 wt % when used in the lowermost layer.
The blueing agent is incorporated in the water-resistant resin by a kneader
such as a two-roll, a three-roll, a kneader, a Banburry mixer, or a
continuous kneader (such as a stone grist mill-type, a planet-type, a
roll-type, or an internal mixer). The obtained water-resistant resin
containing the blueing agent is formed in a pellet shape and used as a
master batch which contains the blueing agent.
The density of the blueing agent in the pellet is preferably about 1 to 30
wt %. The titanium dioxide pigment may be kneaded together into the pellet
when the pellet of the blueing agent is formed. Further, in order to aid
dispersion of the blueing agent, a dispersion aid such as a low molecular
weight water-resistant resin, a polyolefine wax, a higher fatty acid
metallic salt, an ester of higher fatty acid, a higher fatty acid amide,
or a higher fatty acid can be used.
An antioxidant may be incorporated in the water-resistant resin coating
layer of the present invention. The content of the antioxidant with
respect to the amount of the water-resistant resin is preferably about 50
to 1,000 ppm.
A water-resistant resin used in the present invention can be used by
heating and melting a pellet which contains the aforementioned titanium
dioxide pigment and by the pellet being diluted with the water-resistance
resin as needed. Further, the pellet which contains the titanium dioxide
pigment can be used together with a pellet which contains the blueing
agent as needed. Then, the single or multi-layer water-resistant resin
coating layer in the present invention is formed on a substrate such as
paper or synthetic paper by laminating the obtained water-resistant resin
by a method such as an ordinary laminating method, a serial laminating
method, or a laminating method which uses a single or multi-layer
extruding die such as a feet-block type, a multi-manifold type, or a
multi-slot type. The shape of the single or multi-layer extruding die is
not particularly limited. However, generally a T die, a coat hanger die,
or the like is preferably used.
Before the resin is coated on the substrate, the substrate is preferably
subjected to an activation treatment such as a corona discharging
treatment, a frame treatment, a glow discharging treatment, or a plasma
treatment.
When the water-resistant resin coating layer of the present invention is
formed by, for example, three layers, the thickness of the uppermost layer
is preferably 0.5 to 50 .mu.m, that of the intermediate layer is
preferably 5 to 50 .mu.m, and that of the lowermost layer is preferably
0.5 to 50 .mu.m.
The outermost layer of the water-resistant resin coating layer at the side
at which an image is formed may have a glossy surface, a fine surface
described in Japanese Patent Application Laid-Open (JP-A) No. 55-26507, a
matte surface, or a silky surface, and the reverse layer thereof may have
a non-glossy surface. These surfaces can be made by using a roll or the
like which has, for example, the glossy surface, the fine surface, the
matte surface, or the silky surface. An activation treatment such as
corona discharging treatment, frame treatment, or the like can be applied
to the top surface after formation. Further, after the activation
treatment, an undercoating treatment can be applied.
Examples of the substrate used in the present invention include: a natural
pulp paper having ordinary natural pulp as a main component; a mixed paper
of natural pulp and synthetic fiber; a synthetic fiber paper having
synthetic fiber as a main component; a so-called synthetic paper in which
a synthetic resin film such as polyethylene, polyethylene terephthalate,
or polypropylene has been formed like paper. However, as a substrate for
photographic printing paper, use of natural pulp paper (simply referred to
as base paper hereinafter) is particularly preferable.
Examples of chemicals which may be added to the base paper include: an
alkyl ketene dimer, a filling agent such as clay, talc, calcium carbonate,
or an urea resin particulate; a sizing agent such as rosin, a higher fatty
acid salt, a paraffin wax, or alkenyl succinic acid; a paper stiffener
such as polyacrylamide; and a fixer such as aluminum sulfate. In addition,
a dye, a fluorescent dye, a slime control agent, or a defoaming agent may
be added as needed.
The following softening agents can be added to the base paper as needed.
A reference to softening agents can be found, for example, on pages 554 to
555 of the "Shin Shi Kako Binran" ("The New Paper Processing Handbook")
(edited by Shiyaku Time, published in 1980). In particular, a softening
agent having a molecular weight of 200 or higher is preferable. The
softening agent has a hydrophobic group having 10 carbons or more, and is
an amine salt or a quaternary ammonium salt which is self-fixed to
cellulose.
Specific examples of the softening agent include: a reaction product of a
maleic anhydride copolymer and polyalkylenepolyamine; a reaction product
of a higher fatty acid and polyalkylenepolyamine; a reaction product of
urethane alcohol and an alkylating agent; a quaternary ammonium salt of
the higher fatty acid; and the like. However, the reaction product of the
maleic anhydride copolymer and polyalkylenepolyamine, and the reaction
product of urethane alcohol and the alkylating agent are particularly
preferable.
The pulp surface can be subjected to a surface sizing treatment by use of a
film-forming polymer such as gelatin, starch, carboxy methyl cellulose,
polyacrylamide, polyvinyl alcohol, or a degenerated product of polyvinyl
alcohol. Examples of the degenerated product of polyvinyl alcohol in this
case include a degenerated product into which a carboxyl group has been
introduced, a copolymer of a degenerated product into which silanol has
been introduced and acrylamide, and the like. The coating amount of the
film-forming polymer is 0.1 to 5.0 g/m.sup.2, and preferably 0.5 to 2.0
g/m.sup.2.
An antistatic agent, a fluorescent brightener, a pigment, a defoaming
agent, or the like can be added to the aforementioned film-forming polymer
as needed.
The base paper is manufactured according to the following. The
aforementioned pulp and the pulp slurry, to which additives such as the
filler, the sizing agent, the paper stiffener, or the fixer have been
added as needed, are made into paper by a paper machine such as a long
mesh paper machine, then dried and taken up. The aforementioned surface
sizing treatment is performed either before or after the drying. Further,
a calendering treatment is performed between drying and taking-up.
When the surface sizing treatment is carried out after drying, the
calendering treatment can be carried out either before or after the
surface sizing treatment. However, it is preferable to carry out the
calendering treatment as the final finishing process after various
treatments have been carried out. Known metal rolls and resilient rolls
used in the manufacture of ordinary paper are used in the calendering
treatment.
The base paper used in the support for recording sheet of the present
invention is finally prepared by the calendering treatment so as to have a
thickness of 50 to 250 .mu.m. The density of the base paper is 0.8 to 1.3
g/m.sup.3, and preferably 1.0 to 1.2 g/m.sup.3.
In order to prevent electrostatic charge, curling, and the like, various
back coating layers can be coated on the support for recording sheet of
the present invention. Further, the back coating layer can contain
appropriate combinations of inorganic antistatic agents, organic
antistatic agents, hydrophilic binders, latices, hardening agents,
pigments, surfactants, and the like which are disclosed or exemplified in
Japanese Patent Application Publication (JP-B) Nos. 52-18020, 57-9059,
57-53940, 58-56859, 59-214849, 58-184144, and the like.
The support for recording sheet in the present invention, being coated with
various photographic structuring layers, is used for a color photographic
printing paper, a monochrome printing paper, a photocomposing printing
paper, a reversal photographic material, a negative or positive image
receiving layer of a silver salt diffusion transfer process, or, being
coated with a multicolor heat-sensitive layer and an image receiving layer
of various inks and pigments, is used for a color heat-sensitive material,
an ink jet sheet, a heat-sensitive transfer sheet, a color Xerox, or the
like.
The present invention will next be described by way of Examples, which
should not be construed as limiting the invention.
The silane coupling agents in the Examples are as follows. n, R.sup.1, and
R.sup.2 are defined by the same definitions of n, R.sup.1, and R.sup.2 of
formula (1).
TABLE 1
silane
coupling
agent n R.sup.1 R.sup.2
A 1 CH.sub.3 (CH.sub.2).sub.5 CH.sub.3
B 2 CH.sub.3 (CH.sub.2).sub.4 CH.sub.3
C 1 CH.sub.3 CH.sub.3
D 1 C.sub.2 H.sub.5 CH.sub.3
EXAMPLES
Example 1
Using a cooling roll having a surface matte roughness of 10 .mu.m, a single
layer of polyethylene resin of the composition indicated in Table 2 below
was extruded at a molten discharge film temperature of 320.degree. C. and
at a line speed of 250 m/min and laminated onto the reverse surface of a
paper substrate having a width of 3m and a mean weight of 169 g/m.sup.2,
and which had been treated by a corona discharge having an output of 17
kw. The resultant polyethylene resin layer had a thickness of 27 .mu.m.
TABLE 2
Amount of
Composition MFR (g/10 min.) Density (g/cm.sup.3) Additives (wt %)
HDPE 12 0.967 50
LDPE 3.5 0.923 50
Next, using a cooling roll having a surface matte roughness of 0.7 .mu.m, a
mixture of LDPE (the same as that in Table 2) and two types of pellets
mixed in such a way as to produce the final composition shown in Table 4
was extruded at a line speed of 250 m/min. and laminated onto the top
surface of a paper substrate at the side at which an image was formed so
as to prepare a coating layer of the water-resistant resin. One of the
types of the pellets thus mixed was master batch pellets of LDPE (the same
as that in Table 2) and titanium dioxide, with the titanium dioxide having
been treated with aluminum phosphate with respect to the titanium dioxide
(0.05% by weight) and a silane coupling agent with respect to the titanium
dioxide (1.0% by weight). The other type of pellets thus mixed was master
batch pellets which included 5% of ultramarine blue. Thereafter, a corona
discharge treatment having an output of 18 kw was administered to the top
surface of the resultant laminate, and a corona discharge treatment having
an output of 12 kw was administered to the reverse surface of the
resultant laminate, and a support for recording sheet was thus formed. At
this time, a titanium dioxide pigment applied by a silane coupling agent
by a wet process treatment was used as described below.
TABLE 3
Composition Content (wt %)
LDPE (p = 0.921 g/cm.sup.3) 37.98
TiO.sub.2 60
Zinc stearate 2
Antioxidant 0.02
TABLE 4
Amount of Resin
Additives Thickness temperature
Composition (wt %) (.mu.m) (.degree. C.)
LDFE (.rho. = 0.921 g/cm.sup.3) 67.7 28 326
Titanium dioxide pigment 30
anatase-type TiO.sub.2
surface treatment amount
aluminum phosphate: 0.05 wt %
silane coupling agent A: 1.0 wt %
Zinc stearate 2
Ultramarine blue 0.3
Production of the titanium dioxide pigment:
Anatase-type titanium dioxide having a mean particle diameter of 0.16 .mu.m
according to an electron microscope was prepared in an aqueous slurry of
300g/1 as the density of solids of the titanium dioxide. A predetermined
amount of aluminum phosphate (see Table 4) was added to the slurry while
the slurry was maintained at a temperature of 40.degree. C., and then the
titanium dioxide in the slurry is treated by the aluminum phosphate.
After the pH of the slurry was adjusted to 3, a silane coupling agent A to
D was added to the slurry in a predetermined amount (see Table 4, and
Examples and Comparative Examples described later) with respect to the
weight of the titanium dioxide. The resultant slurry was then stirred and
hydrolyzed.
Next, this slurry was heated to 80.degree. C., stirred, and thereafter
filtered and washed. The obtained cake of titanium dioxide was dried at
120.degree. C. for 12 hours and ground by a jet mill, and a titanium
dioxide pigment was obtained.
Example 2
A support for recording sheet was prepared in the same manner as in Example
1 except that the treatment amount of aluminum phosphate with respect to
titanium dioxide was 0.1 wt %, and titanium dioxide was treated by the
silane coupling agent B in an amount of 0.8 wt %.
Example 3
A support for recording sheet was prepared in the same manner as in Example
1 except that the treatment amount of aluminum phosphate with respect to
titanium dioxide was 0.5 wt %, and titanium dioxide was treated by the
silane coupling agent C in an amount of 0.8 wt %.
Example 4
A support for recording sheet was prepared in the same manner as in Example
1 except that the treatment amount of aluminum phosphate with respect to
titanium dioxide was 1.0 wt %, and titanium dioxide was treated by the
silane coupling agent D in an amount of 0.8 wt %.
Example 5
A support for recording sheet was prepared in the same manner as in Example
1 except that the treatment amount of aluminum phosphate with respect to
titanium dioxide was 0.5 wt %, and titanium dioxide was treated by the
silane coupling agent A in an amount of 0.5 wt %.
Comparative Example 1
A support for recording sheet was prepared in the same manner as in Example
1 except that the treatment amount of aluminum phosphate with respect to
titanium dioxide was 0.01 wt %.
Comparative Example 2
A support for recording sheet was prepared in the same manner as in Example
1 except that the treatment amount of aluminum phosphate with respect to
titanium dioxide was 1.5 wt %.
Comparative Example 3
A support for recording sheet was prepared in the same manner as in Example
1 except that, in place of aluminum phosphate, sodium aluminate and
sulfuric acid were used to apply Al.sub.2 O.sub.3 in an amount of 0.1 wt %
with respect to titanium dioxide to the TiO.sub.2 surface, and titanium
dioxide was treated by the silane coupling agent A in an amount of 0.8 wt
%.
Comparative Example 4
The support for recording sheet was prepared in the same manner as in
Example 1 except that, in place of aluminum phosphate, sodium aluminate
and sulfuric acid were used to apply Al.sub.2 O.sub.3 in an amount of 0.5
wt % with respect to titanium dioxide to the TiO.sub.2 surface, and then,
the TiO.sub.2 was sprayed with a methanol solution of trimethanol ethane
while being ground by the jet mill.
Comparative Example 5
The support for recording sheet was prepared in the same manner as in
Example 1 except that, in place of aluminum phosphate, sodium aluminate
and sulfuric acid were used to apply Al.sub.2 O.sub.3 in an amount of 0.5
wt % with respect to titanium dioxide to the TiO.sub.2 surface and
titanium dioxide was not treated by silane coupling agent.
The support for recording sheet thus obtained were examined with respect to
film cracking traces and die-lip stripes during lamination of the
water-resistant resin coating layer at the image printing side, sharpness
of image, light fading resistence of the surface to be printed when
exposed to sunlight. The results are shown in Table 5.
Evaluation standards are as follows:
.circleincircle.: excellent level of production suitability or commercial
value
.largecircle.: good level of production suitability or commercial value
.DELTA.: somewhat inferior level of production suitability or commercial
value
X: no production suitability or commercial value
TABLE 5
Occurrence
Trace of film of die-lip Image Light fading
cracking stripes Sharpness resistance
Example 1 .circleincircle. .smallcircle. .circleincircle. .smallcircle.
Example 2 .circleincircle. .circleincircle. .circleincircle.
.smallcircle.-.circleincircle.
Example 3 .circleincircle. .circleincircle. .circleincircle.
.circleincircle.
Example 4 .circleincircle. .smallcircle. .circleincircle.
.circleincircle.
Example 5 .circleincircle. .circleincircle. .circleincircle.
.circleincircle.
Comp.Ex. 1 .circleincircle. .DELTA. .circleincircle. X
Comp.Ex. 2 .DELTA. X .circleincircle. .circleincircle.
Comp.Ex. 3 .circleincircle. .smallcircle. .circleincircle. .DELTA.
Comp.Ex. 4 .smallcircle. X .circleincircle. .smallcircle.
Comp.Ex. 5 .DELTA. .DELTA. X .smallcircle.
As Table 5 clearly indicates, the support for recording sheet of the
present invention exhibits either excellent or good levels of production
suitability or commercial value with respect to each of the properties
mentioned above. On the other hand, when conventional titanium dioxide is
used, levels of production suitability or commercial value become either
somewhat inferior or non-existent for at least one of the properties
mentioned above.
As described above, in accordance with the present invention, it is
possible to provide a support for recording sheet in which there is no
film cracking, the occurrence of die-lip stripes is inhibited, which has
excellent image sharpness, and in which excellent light fading resistance
can be maintained.
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